Unlike Python, TypeScript/JavaScript has a wide variety of module import and export methods.

Currently, ES6 has been standardized, so using import/export is recommended. Due to historical legacy and the huge number of npm libraries, require/exports will continue to coexist for a long time.

1. ES6 Module Import and Export

1.1. Syntax

Three export methods, two import methods

export import
export var; import {var} from module
export {var}; import {var} from module
export default var import var from module

You can also use:

import * as module_alias from module

This imports all exported variables from the module into an object called module_alias.

1.2. Examples

1.2.1. testEs6Export.ts

'use strict'
//Export variable
export const a = '100';  

 //Export function
export const dogSay = function(){ 
    console.log('wang wang');
}

 //Export function - second way
function catSay(){
   console.log('miao miao'); 
}
export { catSay };   

//export default export
const m = 100;
export default m; 
//export defult const m = 100;// This format cannot be written here.

1.2.2. index.ts

import { dogSay, catSay } from './testEs6Export'; //Imported exported methods 
import m from './testEs6Export';  //Imported export default 

import * as testModule from './testEs6Export'; //As aggregated object export

2. CommonJS Module Import and Export

2.1. Syntax

The module has a module.exports object, which contains the exported variables.

exports = module.exports = {};

Additionally, there is exports, which is a reference to module.exports.

Use require to retrieve the variables exported by the module.

Note: The actual export is the variable that module.exports points to.

2.2. Example

//utils.js
let a = 100;

console.log(module.exports); //Can print result: {}
console.log(exports); //Can print result: {}

exports.a = 200; //Here, the hard work changes module.exports content to {a : 200}

exports = 'point to other memory area'; //Here, exports is pointed elsewhere

//test.js

var a = require('/utils');
console.log(a) // Prints {a : 200}

3. References